US House Budget Committee Chairman Rep. Paul Ryan, R-Wisc., is a member of a bicameral committee tasked with coming up with a compromise on the US budget. (Chip Somodevilla/Getty Images)

WASHINGTON — With a US debt default averted and a government shutdown ended on Oct. 16, focus on Capitol Hill quickly shifted to a high-level panel charged with crafting a budget plan within two months.

As the smoke cleared from several weeks of partisan bickering and Senate Republicans feuding with their House colleagues, lawmakers did what they so often do: They pledged to have learned their lesson and predicted brighter days that will finally yield a meaningful budget plan Republicans and Democrats will support.

“I think the tone went over the cliff, and now everyone realizes that they were losers. The Republicans were bigger losers, but the president and Democrats also lost,” Senate Armed Services Committee member Sen. John McCain, R-Ariz., told Defense News on Oct. 17.

“I’ve already detected a new kind of attitude of, ‘Let’s not do this again because it hurt all of us and maybe we ought to start talking more,’ ” McCain said. “That group of 14 senators, there were many other who wanted to join that group. There’s momentum in that direction.”

McCain was referring to a bipartisan group of senators that that helped produce the default-avoiding, shutdown-ending legislation.

But beneath the upbeat pronouncements is a years-old chasm over issues that separate the parties on ideological grounds: tax rates, domestic entitlement programs, health care and defense spending.

Congress’ last-minute fiscal deal set up three major deadlines: A House-Senate budget panel must report spending recommendations by Dec. 15; a temporary government-funding measure expires on Jan. 15; and the debt ceiling must again be raised by Feb. 15.

With the parties still bitterly divided, expect the rosy talk to give way to not one, not two, but three political fights bitter as Washington’s winter winds.

“We want to look for ways to find common ground, to get a budget agreement,” House Budget Committee Chairman Rep. Paul Ryan, R-Wisc., a member of the bicameral panel, said after its leaders met over breakfast on Oct. 17.

“Our goal: Is it good for the American people to get the debt under control, to do smart deficit reduction, and to do things that we think can grow the economy and get people back to work.”

Senate Budget Committee Chairwoman Sen. Patty Murray, D-Wash., said the conference committee leaders “believe there is common ground and showing the American people that Congress can work, and make sure that our economy is growing and that people are back to work.”

Democrats enter the budget talks eager to replace the remaining parts of twin $500 billion sequestration cuts to defense and domestic spending with other deficit-paring items. But senior Republicans made clear they will insist on locking in defense and domestic spending cuts set by the 2011 Budget Control Act, and make Democrats prove any items to replace the cuts to get under those caps are “real” and not gimmicks.

“We’re protecting the government spending reductions that both parties agreed to under the Budget Control Act, and that the president signed into law,” Senate Minority Leader Sen. Mitch McConnell, R-Ky., said on Oct. 16. “That’s been a top priority for me and my Republican colleagues throughout this debate. And it’s been worth the effort.”

The panel’s work — and coming budget fights after it delivers its recommendations — will pit congressional defense hawks against fiscal conservatives, and align the pro-defense members with Senate Democrats.

The push to replace the sequester is creating strange bedfellows on Capitol Hill, something that likely will continue throughout the winter.

The upper chamber’s Democrats are pushing to replace the sequester cuts, something House and Senate defense hawks have pushed for two years.

Last month, House Armed Services Committee Chairman Rep. Buck McKeon, R-Calif., and Senate Democrats opposed including language in the emergency fiscal bill that would have given Pentagon leaders the ability to decide what gets cut under sequestration.

Why? They feared such flexibility would make sequestration too tolerable to some to garner ample support to get rid of it.

Asked if Senate hawks are more closely aligned with Senate Democrats on rolling back the sequestration cuts, McCain replied, “Yeah. Yeah.”

“I say this with respect to my friends in the House: ‘If something is going to happen, it’s going to have to happen here.’ ”

McCain in recent weeks has harshly criticized his House GOP mates for their tactics that led to a government shutdown and then pushed the nation toward a debt default.

The House-Senate budget panel will have to grapple over thorny partisan issues as its tries to cobble together a bipartisan budget plan.

It didn’t take long for both parties to revert to the stances that have prevented a “grand bargain” fiscal deal that would replace sequestration with other items.

“I can’t raise the debt ceiling for so little in return, I’m looking to delay the individual mandate with Obamacare,” Rep. Renee Ellmers, R-N.C., one of the fiscal conservative tea party members elected in 2010. “I’m looking for more spending cuts.”

Levin and other Democrats trotted out their preferred description of a budget plan both parties could support: “You got to have a mixture, you’ve got to substitute a balanced combination of targeted cuts, maybe much smaller than the ones that are in sequestration plus some additional revenues plus entitlement reform. you need a balanced combination of all three.”

And because the annual Pentagon budget will remain above $500 billion each year beyond 2014 even with sequestration, two senior pro-Pentagon senators aren’t ruling out some amount of defense cuts in a bipartisan deal.

Asked if some amount of defense cuts can be avoided, McCain said: “I’m not sure.”

Levin was more precise, predicting the remaining amount — about $450 billion — of defense sequestration could be shrunk.

“I think there will be, hopefully,” he said, “a much, much smaller cut not only for defense but the other discretionary programs.”